[SOLVED] Reading umask (thread-safe)

I know this pattern to read the umask in Python:

current_umask = os.umask(0)  # line1
os.umask(current_umask)      # line2
return current_umask         # line3

But this is not thread-safe.

A thread which executes between line1 and line2 will have a different umask.

Is there a thread-safe way to read the umask in Python?

if your system has Umask field in /proc/[pid]/status, you could read from on it:

import os

def getumask():
    pid = os.getpid()
    with open(f'/proc/{pid}/status') as f:
        for l in f:
            if l.startswith('Umask'):
                return int(l.split()[1], base=8)
        return None

tested under CentOS 7.5, Debian 9.6.

or, you could add a thread lock :)